Height-adjustable hospital or nursing beds use known telescopic lifters for the height adjustment, besides other lifting devices.
European patent EP 0982 018, the disclosure of which is incorporated by reference, deals with such a telescopic lifter containing a fixed part in which the first extensible part is concentrically arranged and in the first part another extensible part is concentrically arranged. At the upper end of the first extensible part a pulley is installed over which a chain is routed whose one end is attached to the fixed part and the other end is attached to the lower end of the other extensible part. Another pulley is attached to the lower end of the first extensible part and over it a chain is routed whose one end is attached to the upper end of the fixed part and the other end is attached to the upper end of the second extensible part. The drive may consist of a motion screw with a nut. In such a case in the lower part of the fixed part a worm gear is installed in a turning way on a bearing. The worm gear is firmly interconnected with the motion screw on which a nut is installed that is firmly connected to the first extensible part. The first extensible part is secured against turning with a vertical guide. An electric motor turns the worm gear via a worm and consequently the motion screw as well. Depending on the turning direction of the motion screw the action of the nut either slides the first extensible part upwards or downwards. At the same time the pulleys move, too, so rolling of the chains over the pulleys makes the other extensible part move in the same direction.
In known hospital or nursing beds with the possibility of positioning or height adjustment a lot of cables are routed between electric elements on the undercarriage of the bed (e.g. drive of a telescopic lifter or electric elements of the undercarriage) and electric elements on the patient surface of the bed (e.g. adjustment motors of the backrest or legrest or controls). These in principle loose cables represent the source of a lot of problems as during the adjustment of the position of the bed they may get damaged.
It is not possible to merely slip the cable through the inside of the known telescopic lifters as during the extension and retraction of the telescopic elements the electric cable may get damaged.
The aim of the invention is to modify the known lifter in such a way as to enable routing of a multi-conductor cable that interconnects electric elements on the undercarriage of the beds and electric elements on the patient surface through the lifter.